Signal level of cable modem dropping

At one point, my Motorola SB6121 cable modem had levels at +2dBmV or higher.  A service tech came out and put a pad inline dropping levels to 0dBmV on all channels.  Now it has dropped -2 to -3dB per channel.  I haven't noticed any changes in working, but should I make a service call to have the pad removed?