Paychex falls after first-quarter results

** Payroll services provider Paychex's PAYX.O shares fall 6.6% to $107 premarket

** Co reports Q1 sales of $1.630 bln, vs. analysts' avg. estimate of $1.627 bln

** Reports Q1 sales in Management Solutions of $1.21 bln, vs. estimates of $1.23 bln

** Q1 adj. EPS comes in at $1.34 vs. estimates of $1.32

** Up to last close, stock has risen 2.1% YTD