You mentioned medication in a recent post. If you are taking medication it could be from that. The advice I was given for that was to add salt to my meals and stand up slowly.
If it's bothersome and you're concerned about it then you should discuss it with your own doctor.
I was told that anxiety affects carbon dioxide levels which effects blood pressure.
Some regular physical exercise or activity may help manage the anxiety a little better. (I probably wouldn't include tiling as a relaxing form of activity.) Try adding a walk or something else you enjoy -it doesn't have to be very long.
Your blood pressure is fine even with your anxiety?? You must be doing something right (plus have good genetics).
I hope this resolves itself.
I can't make a diagnosis at a distance, but look up posturual hypotension, because that what it sounds like.
Oh, and I have frequent panic attacks and feel anxious a lot. everytime I go to the doctors my blood pressure is fine, I have the occasional heart palpatation ( I assume from my anxiety) I dont excersize regularly, I dont eat terrible foods, I have a decent diet, and I had also eaten breakfast today.