LiB
If you have a look at the descriptors in the ESA claims on Physical Grounds, page 32, you'll see that the relevant tests are for 30 minutes and an hour, so 1-10 minutes is well with these.
However, if you think it important, you can write to your local DWP office with the update (c/o the Decision Maker), and take a copy of the letter with you to your medical, assuming you have one.
Make sure you include your full name and NIN on each page of the letter, and as always with the DWP, send by Recorded Delivery or get a certificate of posting.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
