Impact of permanent magnet on component storage
Many transistors (and other through-hole components) are made with tin/copper plated steel leads to save on copper, that's why they are attracted by magnets. Static magnetic field won't have noticeable effect on transistors themselves, but residual magnetic field can affect sensitive components nearby, like hall sensors or reed relays. This is especially important if you tend to make high-density designs, you're unlikely to notice any effects at all if your components are a couple centimeters apart.

Also, as @mkeith said in his comment, designs with moving parts may exhibit some interference from induced EMF. Again, this is unlikely to be noticeable unless you have compact design and parts of it are moving or spinning very fast. Most probably, motors used in such design will produce much more interference than residual magnetism on transistor leads.

Needless to say, sensitive components themselves should not be stored near magnets.