I tested positive for syphilis 5 years ago and have tested negative since then. i recently got tested and was found reactive and positive with 1:1 tier. there has been no exposure. is that abnormal or normal? should i be worried?

This usually is normal: when RPR or VDRL titer becomes negative, it is not rare to fluctuate thereafter between negative and barely positive. To play it safe, have another test in the next 1-2 months; if still 1:1 or negative again, all is well. If the titer rises to 1:2 (and especially if 1:4 or higher), see a syphilis expert, such as an infectious diseases specialist. Good luck.