If i lay down flat for three minutes and take my blood pressure it is 123/86. if i stand up, and remain still, and wait three minutes it goes up to 142/107. is this normal? i'm taking the lowest dose of valsartan daily?

BP is highly variable. Both these numbers are higher than desired: 123/86 is only slightly elevated but you definitely don't want it near 142/107 most of the time. Keep taking your BP a few times a day, in various positions, and keep a record of the results. When you have several days' data, show the record to your doctor and then discuss possible changes in your treatment. Good luck.