it's not that small,i was in the pool

thought i'd start a thread because i'm looking for input...i'll be getting my tsb rears(4pk) friday,i'd like to also add 5100's all around on my 2010 trd sport(4 dr/sb/v-6/auto trans/2wd prerunner).i went to two different toyota lots in my area on sunday and measured ground to fender flare height,these measurements were consistantly 1 inch higher in front that my identically equipted 2010(17 in wheel option)....the trucks that were measured were 2012/13....the rears were also consistantly 1.5/1.75 in higher than mine as i have the old 3 leaf pak currently..even without measureing you could see that the newer truck sits higher...i spoke with one of the local parts guys at a dealership and he said the part # for '10 thru 13 were the same. so my question is..WHAT HAPPENED TO MY INCH!at barely 36000 mi. on a lightly driven street truck,could there possibly be sagging/fatigue of the stock spring.i'd like to keep the 5100's @ zero...but i think i may be too"butt-high"with the tsb and zero 5100....BUT if new"FACTORY" front springs give me that 1 inch back i'll be close to factory rake with out pre-loading the bilsteins and hopefully avoiding any alignment or warranty issues...i know i could go with "ome" or eibach but i don't think i want a spring with such a high spring rate,and i don't want anymore that an inch or so to hopefully get back to near stock rake...the stock springs are more expensive but i'd gladly pay that extra cash for a worry-free lift...540 lb springs sounds a bit better to me than 620's