Absolutely! It's down to STRESS, STRESS, STRESS. Over the past few months I've found out that merely thinking about something can affect very real changes / sensations / appearances in your body. Especially if it's the arm hanging by your side, I wouldn't worry about it, just blood flow - like if you swing your arms around and the hands go sort of speckly. I had this worry myself, and it came to absolutely nothing. No worries.