Loosing 4 seconds per day (28 per week) falls within the bounds of accuracy required of a Swiss certified mechanical chronometer and is pretty good.

https://en.wikipedia.org/wiki/COSC

[I made a similar comment further down.]

Nope... came from Germany that way.

As other have notes though losing ~4 seconds a day is pretty accurate all things considered. Seiko's 3Hz movements can gain or lose _half a minute_ a day and still be considered within spec.

That seems surprising bad. Maybe not strictly out of tolerance, but definitely something that could be considerably improved by having the movement regulated (or perhaps serviced, if required). Is it still under warranty?

Not from the manufacturer, no. I bought it second-hand and the seller does offer a 36-month warranty for any mechanical dysfunctions, though I'm not sure whether something like this would qualify. Even if it did, I'm not all that enthused about bearing the costs of sending the watch to way across Europe if it could just be regulated by my local watch shop instead. Am I understanding correctly that if I had it regulated, then it the deviation would be minimal for years to come or how exactly would that pan out accuracy-wise?