I just checked back and saw that you had replied, so I'd like to send you more information.
Because Lil Bit spends time outside, it's possible that her nose DID become sunburned, or she may have been bitten or stung by an insect. However, her nose would most likely be swollen or painful and she'd exhibit discomfort on her nose.
I've never been aware of any feline cardiac condition causing the nose to turn red; if anything, it would be the opposite, the nose, gums, tips of the ears, would turn paler, in cases of heart disease, since a circulation problem would be present and/or the blood would be less oxygenated.
Here is some information regarding heart disease in cats, and initial symptoms:
I don't doubt your online friend's report re: her kitties with red noses then being diagnosed with heart disease, and I'm so sorry to hear about the loss of her one furry boy; however, at this time, I would suggest a complete senior examination, including blood work, for Lil Bit, ASAP, and that should put your mind at ease, if all is well. If Lil Bit is found to have a heart condition, or any other medical condition, you've caught it in time to begin treatment.
I hope all will be well with Lil Bit!
Would you please let me know how she's doing and what the vet's findings are? Thanks!