To answer your question: Yes. You are facing two problems:
1) ECB is inherently unsafe to use and is only meant to be used as a building block for more safe operations. ECB mode produces the same output for the same input each time so it is extremely deterministic.
2) Because of the properties mentioned in 1 it will become trivial for an attack to determine what you exact padding is when he gathers a bunch of texts.
You should really consider using a more complex operation mode.
I strongly suggest that you use CBC (Cipher Block Chianing) or any of the other more secure modes (OFB, CFB, CTR) <- look these up if you have to.
EDIT: I made you a list down below that references wikipedia and also explains that ECB should not be used:
The simplest of the encryption modes is the Electronic Codebook (ECB)
mode. The message is divided into blocks, and each block is encrypted
separately. The disadvantage of this method is that identical
plaintext blocks are encrypted into identical ciphertext blocks; thus,
it does not hide data patterns well. In some senses, it doesn't
provide serious message confidentiality, and it is not recommended for
use in cryptographic protocols at all.
In CBC mode, each block of plaintext is XORed with the previous
ciphertext block before being encrypted. This way, each ciphertext
block depends on all plaintext blocks processed up to that point. To
make each message unique, an initialization vector must be used in the
first block. CBC has been the most commonly used mode of operation.
Its main drawbacks are that encryption is sequential (i.e., it cannot
be parallelized), and that the message must be padded to a multiple of
the cipher block size. One way to handle this last issue is through
the method known as ciphertext stealing. Note that a one-bit change in
a plaintext or IV affects all following ciphertext blocks.
The Cipher Feedback (CFB) mode, a close relative of CBC, makes a block
cipher into a self-synchronizing stream cipher. Operation is very
similar; in particular, CFB decryption is almost identical to CBC
encryption performed in reverse.
The Output Feedback (OFB) mode makes a block cipher into a synchronous
stream cipher. It generates keystream blocks, which are then XORed
with the plaintext blocks to get the ciphertext. Just as with other
stream ciphers, flipping a bit in the ciphertext produces a flipped
bit in the plaintext at the same location. This property allows many
error correcting codes to function normally even when applied before
Like OFB, Counter mode turns a block cipher into a stream cipher. It
generates the next keystream block by encrypting successive values of
a "counter". The counter can be any function which produces a sequence
which is guaranteed not to repeat for a long time, although an actual
increment-by-one counter is the simplest and most popular.