Any US military aircraft landing/refueling in Ireland?

They don't need to, really. Long-range bombers like the B-52 or B-1 can make the trip from the US to Europe without refuelling. The same goes for airlift aircraft like the C-17, C-130, or C-5. Fighter aircraft will likely either rendezvous with a mid-air refuelling tanker somewhere over the Atlantic or be accompanied by one, such as a KC-46, for the entire trip.

Also, why would you land in Ireland when you have secure bases like RAF Fairford or RAF Lakenheath just thirty more minutes of flying time further to the east? Whilst both of these are technically RAF bases, they've been hosting US squadrons and detachments for ages at this point, so they're properly secure, have the necessary maintenance, refuelling and re-arming facilities to properly service, for example, a six-aircraft flight of F-15s that have just come in from the US, and provide proper housing and dining facilities to allow for the pilots to recover as well. None of that is present here in Ireland.

What Ireland, more specifically Shannon, does get is civilian airliners chartered in by the Pentagon to transport soldiers and/or their dependents into an out of Europe or the Middle East. However, those are just that, civilian aircraft owned by civilian airlines and operated by civilian crews, the only thing military about them is the passenger list. The only time I've seen actual US Air Force aircraft land in Ireland was when they were either related to a government visit or due to an emergency landing.

No warplanes landed in Shannon. There were large movements of troops, as Thomil has pointed out using civlian charters.

Probably weather related, needing to top up their tanks before going transatlantic. Just checked some websites, and it looks like there are some pretty considerable headwinds for aircraft flying westwards across the Atlantic, down to relatively low levels. I'm talking beyond usual jet stream levels…

Aircraft such as the C-130 Hercules, which @PreCocious posted a screenshot of, will need to have full tanks before going transatlantic, so I guess they dropped in to top off their tanks. Interestingly, the aircraft in question, which is supposedly headed to Halifax, is flying a southerly course that should take it away from the worst headwinds, but also means a longer flying time and a need for more fuel.