Think of a shortened antenna as being the same as turning down the hearing aid on your airplane. It can still 'hear' the transmitter, just not as well. I don't think that 1/2" will make a huge difference. But, as TimC said, it wouldn't be a bad idea to bring it back to full length.

You can lose that 6" that Downtrodden mentioned, but as he points out, that plane was flying close in. It would probably fly further out, but again, it would be more 'deaf' than an airplane that had a full antenna.

It's not the end of the world, just not a good thing to do....

Bob