Not really. People underrate how great a grass court player Nadal is. By far the 2nd best of this era behind Federer, much superior to Djokovic or Murray career wise at this point. So Nadal winning all the clay and all the grass meetings doesnt surprise me much. Hard courts Nadal is also underrated and is atleast on par with Murray career wise, so again not surprised he could win half and even slightly lead the H2H on hards.
Anyway as others have said there isnt anything that would logically make Murray a tough matchup for Nadal. Nadal mostly has problems with guys who can overpower him.