dead rat

Question
hi. i had two healthy male rats. not sure how old they are (were). i've had them 3.5 months, the lady i got them from said she had them 2 months and had seen them in a pet store for a few months before that. last friday evening, i came home to find the (i thought) thinner, more active healthier ratty lying dead on the cage floor. he'd had no wheezing or any signs of distress earlier that day, in fact he was his usual playful, active self. i was at an open mic for a few hours and got home, he'd been dead a little while as he was stiff and getting cold. i tried looking down his throat to see if he'd choked, but couldn't see very far down. the only thing i noticed about him was he was lying down in a seemingly peaceful pose, however, his tongue was swollen and kind of stiking out around his teeth.
so i am desperate to know what could have killed my seemingly happy, healthy little baby so suddenly? again, i don't know how old they are (were) so maybe it was old age? or does the bloated tongue mean he choked on some piece of food? the other one seems fine, but i plan on taking him to a vet next month when i have some money just in case. thanks.

Answer
I am very sorry for your loss.  

I know this sounds a bit harsh, but its actually better to lose rats this way rather than see them suffer with some of the terrible illnesses that they are prone to developing.  

With his age and all, chances he died from something such as a brain aneuyrysm or from an underlying heart problem is pretty high.  He probably had a heart attack or a brain aneurysm and it was over pretty fast.   I have lost several rats this way and have had a necropsy done on them and the findings were pretty much what I thought: heart attack or brain aneurysm.

Rats dont usually choke to death, its just not super common.

Again I am so sorry for your loss!