if it's not irritated on the outside from rubbing, i would say you need to get it checked out. Like PO5 i have had one from a lot of coughing when i was sick - was pretty awesome actually once we realised what it was (the whole white of my eye went red - looked awesome! lol)! but, with nothing like that going on, it may be that you've had a period of high BP that is causing micro-vessels to burst - best to get on top of it and at least get it checked just in case there is something more going on kwim?