sounds like you didnt use enough hardener to get the reaction going as quickly as it should have, but as long as you put in the catalyst and thoroughly mixed it with the resin you should be fine. is it sticky, but stronger than before? if it doesnt feel strong, i'd suggest upping the amount of catalyst and doing another coat. obviously this one would cure faster (and if you put in too much catalyst, WAY TOO FAST), so be aware that you'll need to move quickly but do a good job as well. the reaction occurs faster when under heat, but its better to put it in an area that is consistently hot (not your kitchen oven though) rather than using a heat gun (which unevenly blasts high amounts of concentrated heat). even better, work in a moderate temperature room, then place it in a hot area when you are done brushing stuff on (i used to work on my porch under the awning and then put it on the asphalt under the sun until it cured well.
edit: it may also be sticky just because the reaction has a bi-product, usually there is a stickiness to the glass for a bit after the cure. if that's the case and it feels structurally stronger than before and at a strength you're okay with, then by all means go right ahead and bondo that sucker