<p>Interesting, we called to decline an offer because we had gotten one more generous and the school - within minutes - called back with an additional $10k. For us, the first school was still the better choice for other reasons.<br>
Yes, you need to be careful, but it IS ok to call and discuss the FA - especially if they have gapped you. I would say, if they have not, then it is kind of awkward.</p>