This is a strange question, but is nipple sensitivity normal while on T? I'm not too worried about it right now because of other factors like the weather, but I'm wondering if anyone else has experienced this or if it's common.

It may be a sign that your dose is too high for you. Excess T is converted to estrogen, which can... do things to your breasts. You should probably get your level checked fairly soon -- and if you get any breakthrough bleeding, that's another warning sign to contact your doc.