most likely it's normal.
I have an "intelligent" charger too, manual says once the battery is fully charged it switches to maintenance mode, which is described as light discharging, followed by recharging etc.
this doesn't mean that yours is the same but there's a high probability. as long as it doesn't overcharge or anything, it's most likely ok.
one way to check it is by connecting a multimeter in series and one in parallel and measure current/voltage. normally it should first charge with a constant current equal to rated Ah/10 (for instance if it's 10Ah it should use 1A) or less (mine uses 0.6A since there's no way of knowing the rated Ah) and then switch to constant voltage (current drops exponentially) when a certain voltage is reached. this is the proper way of charging a lead-acid battery. if it's indeed an intelligent charger, chances are it does it this way. what should never happen is to have a voltage across battery higher than ~14.7V. and this figure should be even lower if the charging current is higher than Ah/10.
later edit: looked at the Ctek website, looks like it works just as I described (at the price, it really REALLY should, mine was much cheaper): http://www.ctek.com/Archive/ProductM...S%200.8_EN.pdf