If it takes multiple scrubs with months of delays before it finally launches, then it'll be another thing to add on to Starliner's list of difficulties fulfilling their contract with NASA. However a scrub or two is business as usual.
GSE (Ground Servicing Equipment) are fairly common and fairly benign.
Valves on the rocket? Much, much more rare, and usually indicate some form of issue.
And to be fair to the starcrossed Starliner, the valve "pressure regulation valve on the liquid oxygen tank of the Atlas 54 rocket‘s Centaur upper stage."
https://spaceflightnow.com/2024/05/07/starliner-launch-scrub...
Could be wayward boats and planes, Hydrogen leaks, onboard self diagnostic failure, false hydrogen leak alarms, unstable wireless telemetry connection, upper atmospheric winds and all kinds of weather, frozen plumbings, computers passing out, automatic cutoff due to anomalous vibration at T-1s, anything.
With Soyuz scrubs and failure probabilities finally creeping up, the only vehicle in the world that likely lift off on first try is Falcon 9. Anything else could pause at T-45s and recycle from T-2 hours for couple times, then go all the way to T-0s, and then delay by a week. That's just how most of these things work.
a troubled first few days of October, nicknamed “Scrubtober”, in light of scrubbed launch attempts which have affected SpaceX, Northrop Grumman Corp. and United Launch Alliance (ULA).
https://www.americaspace.com/2020/10/06/spacex-ends-scrubtob...
For anyone who doesn't follow rocket launches, this comment perfectly describes Boeing's Starliner program. Every. Single. Time. it tries to launch there is a non-weather related scrub. Valve issues have been a consistent issue for the capsule, and now it's the booster.