Well it probably isn't a safety problem but it is a nice example of why LEDs are so much more efficient than standard incandescent lights.

The digital timer isn't completely breaking the circuit like an older mechanical timer would (solid state switching vs. relays). Most inexpensive digital timers bleed through a little current when "off". This isn't enough to light your older lights since they require more current to light - typically about 0.24 Amps for 100 modern "efficient" mini-lights. As a comparison LEDs run about 0.067 Amps for the same number of bulbs.

So if your timer is leaking something like 0.02 amp (1.2 watts) when "off" the LEDS will probably glow and while the older lights are "live" they won't light up. This can easily be checked with a digital volt meter but remember to play safe with electricity - at a minimum 120VAC smarts when you accidently join the circuit and the results can be much worse.

Personally I think the glowing would be cool.

- Eric