Staggered Orders: sometimes orders placed with too small spread

## Expected Behavior
Always check spread when placing a new order.

## Actual Behavior
sometimes orders with too small spread are placed and results in "sell low then buy high".

## Steps to Reproduce the Problem

Don't know how to stably reproduce.

## Specifications

  - Version: 1.0.0
  - OS: Ubuntu 18.04 LTS
