There is a reason why pressure gets put on your eye vessels after you toke. It's something to do with the receptors and such, but I'm not a doctor, so I don't know the exact reason.

It's nothing to be alarmed about. It's not bad for you really, but if it is a bother, just go buy some Visine or some good quality eye drops. After you toke and it starts bothering you, just put a few drops in a viola! Taken care of.