I don't really know about Monmouth, but there seems to be a bizarre trend of Republicans surging in Congressional Districts across the country while struggling to hold their leads in Senatorial & Gubernatorial races.
NJ-03 is an R+1 seat. In how many R+1 or greater Senate races does the Republican candidate trail? Zero. Well, one, if you think West Virginia is close. Republicans are struggling to hold their leads in races that are Even or Democratic-leaning. Plus, Senate races are higher profile, so candidate quality matters more.
NJ-06 is a D+8 seat - and Pallone losing is a real stretch.