SOLVED Micro - Power-up behaviour different?

I have three Arduino Micros. One is behaving as expected - it starts the application program immediately after power is applied.
I tested the same at a second Micro and was surprized to see, that it is obviously first running the bootloader after power up, which causes an unwanted delay of several seconds for the application to start. My third Micro also delays to start. This behaviour is the same, either powered per USB (only 5V supply or from PC-USB) - or Vin. I have not access to the first board any more and don't know its revision, the other two missbehaving are R3.
From the specification, the Micro should start the program immediately, the bootloader should be initiated only after a reset or when initalized for programming via USB.
The reset pin is not connected, trying to keep the reset pin additionally puuled up with a 1k resistor as a test does not help.
Any ideas?

After updating the bootloader from the current Arduino IDE 1.0.5-r2, the application sketch is starting immediately after power up.

Real micros or ebay from china micros?

Almost certainly different bootloader versions.

Using an ISP or Arduino as ISP would enable you to examine - or re-load - the bootloader.

Thanks all for the answers.
@bobnova - I hope originals are sold at Conrad, the boards and their packing look OK.
@paul__b - Did not know that it is possible or how to read the existing bootloader version of a board. I have already programmed bootloaders on "naked" processors.
So I will have to do some investigation and try new and/or old firmware.