I think the Republicans should be worried about a "blue wave" come 11/18. https://www.usatoday.com/story/news/politics/2018/03/12/democratic-win-pennsylvania-election-would-referendum-president-trump-and-much-more-because-his-bran/416569002/
Midterm elections, generally you can expect it, that push back. Reps did it to Obama big time in '10, now it's the Dems' turn to do it big time to Trump.
The noteworthy thing is that this is in the "Pennsatucky" part of Pennsylvania, an upset not entirely dissimilar from Doug Jones beating Roy Moore.
Well, except that due to redistricting, Lamb's tenure in the House is likely to be rather short lived.
https://www.thenation.com/article/why-progressives-should-cheer-conor-lambs-victory/ "...thanks to redistricting, he’ll probably face GOP incumbent Keith Rothfus in November, the most secure."