How long has it been sitting out? After a matter of a few hours the rat/mouse will start decomposition and I wouldnt just to be on the safe side - you're looking at maybe a $1 mouse (full grown) or a 20 cent pinky to be saving when it could potentially kill your very expensive snake. I think the risks way outweigh the costs on this one. I have a vacuum sealer as well...I bought it for the sole purpose that I can split up bags of frozen mice and they wont go bad as fast - buy more at one time and save on shipping.
-----
The reason mainstream thought is thought of as a stream is because it's so shallow. -George Carlin
Battling ignorance one stupid person at a time.
Current snakes:
0.1 Licorice Stick Black Rat(Lola)
1.0 Neonate Black Rat (het for Lic Stk's) (Frankie)
1.1 Texas Bairds (Jose and Rosa)
My posts are my opinion only. What you end up doing is your own choice. I will not be held liable for any negative outcome of my advice. (However I will never intentionally give bad advice. My advice is ALWAYS geared towards a positive outcome.)