This is indeed part of having RSD. RSD affects the portion of your brain that processes pain and also other emotions, including the "fight or flight" response. Your adrenalin regulator is starting to be damaged by the RSD.
If you search this forum for "adrenalin", you will pull up some good strings of discussion about this problem from other posters. There are some preventive steps you can take now to prevent the problem from getting worse, or at least slow it down (like meditation, beta blockers, anti-anxiety meds).