For a brand new bike, or ANY vehicle really. The first change or two, typically can have a bit more shavings in them because everything is brand new. All the sharp edges are rubbing off, all the gears are working in with each other. Everything is machining itself in with each other part for the overall mechanism. Now if it keeps doing this change after change or your oil looks like oatmeal with metal sludge, THEN you have a problem, but the first change or two, generally no biggie.
for an electric bike, the gearbox is all you need worry about really, running at 45 mph in urban areas is one thing. Humping it on a race track, or going wot on an open highway for miles is another. Each is going to engage the gearbox at different force vectors, or more intensity on them. This will cause parts that may not have been under heavy load at 45, to load up at 145, and possibly shed a bit as they fine hone and mesh in the gear train.
So, after say 5000 miles, you finally feel confident enough to take your bike for a romp on the track, and you pull metal shavings out the next oil change, don't panic, you just broke in, new parts of the tranny.
this reminds me, I need to check all my stuff again, it's about that time.
Aaron